Writing instruments, such as pens, pencils, and styluses, are used by millions of people every day. Most writing instruments have methods for protecting the writing element in order to prevent users from unintentionally writing with them. For example, some writing instruments have caps, which are one of the simplest of current techniques. Caps fit over the ends of writing instruments to protect and cover the writing element in order prevent unintentional use and/or leaking. Other methods include spring and/or slide assisted mechanisms, which allow retraction of the writing element within the writing instrument, such as with “clicker” pens.
Current techniques to protect the writing element of writing devices are not sufficient in many instances. Caps may be cumbersome (i.e. require two hands, one to hold the pen and the other to remove the cap), may be easy to lose, and may fall off inadvertently. Spring and/or slide-assisted mechanisms may be bulky, require additional parts, be expensive, and/or interfere with the use and function of the writing instrument.
Recently, a self-retaining writing instrument was invented which includes two principal components—a bi-stable spring and a writing element. In the straight configuration, the self-retaining writing instrument is stable enough that it can be used as a typical writing utensil. Secondary to its bistable nature, this writing instrument assumes a coiled configuration when stressed appropriately allowing it to be stored around something, usually, but not exclusively, the user's wrist.
An important feature of the bistable writing instrument is that the writing element needs to be exposed for writing and protected when worn or otherwise not being used. Unfortunately, caps frequently do not stay in place, and spring and/or slide-assisted mechanisms are bulky and not ideal for use with the bistable writing instrument as these may be more costly and, more importantly, interfere with adequate coiling or function of the bistable writing instrument.
Typical writing pens exist only in one configuration and, in general, contain ink cartridges that store writing material in a reservoir that is in fluid communication with the writing tip (i.e. ballpoint). Currently available ink cartridges are also not adequate for use with a self-retaining bistable writing instrument secondary to their inherent rigidity that impedes the ability of the self-retaining bistable writing instrument from assuming its coiled configuration.
Accordingly, there remains a considerable need for an improved method and apparatus for protecting the writing element of a writing device, specifically as relates to the self-retaining bistable writing instrument.